Heat-resisting implement



Talented Jan. 11, 1938 UNITED STATES 8.104.838 HEAT-BESISTING WernerHessenbrueh, Hanan-on-the-Maln, Germany, assignor to iirmReruns-Vacuumschmelze Aktiengeselischait, Hanan-on-the Main, Germany NoDrawing. Original application March i, 1985, Serial No. 9,800. Dividedand this application July 7, 1938, Serial No. 89,871.

March 24, 1934 4 Claims.

This application is a division of my coDending patent application SerialNo. 9,806, tiled Mar. 1935.

This invention relates to heat-resisting implemeats constructed fromalloys of metals or the iron group and the sixth group oi the periodicsystem of the elements.

The heat resistance of implements constructed from alloys of metals ofthe iron group and the E52 merits, e. g., constructed from chrome-nickelalloys is to be ascribed in the first place to the fact that the highchromium content in association with nickel forms a strongly adherentoxide layer which protects the remaining metal from buming. It wasformerly supposed that the heat resistance of implements constructedfrom such alloys could be considerably improved when elements moreelectropositive than nickel, the oxides of which are stable above 1500C. were added thereto. It has, however, been shown that theseconsiderations are by no means generally ap plicable and that althoughcertain of these electropositive elements increase the heat resistance,others on the contrary do not. Thus, for example, the heat resistanceoi' an implement constructed irom a chrome-nickel alloy is considerablyreduced by addition of titanium or also vanadium: even additions ofaluminum bring about improvements of the heat resistance only underparticular conditions, whereas in small quantities they havedisadvantageous influences. Since titanium and aluminum are nearlyrelated to the rare earths, it was consequently to be ex- 35 pected thatthe latter analogously with the former elements would behave in asimilar manner, that is to say would not give rise to any increase inthe heat resistance of implements made of chrome-nickel alloys. Thoroughresearch has now shown that these rare earth metals in contradistinctionto titanium and aluminum have the property of increasing to aconsiderable extent the heat resistance oi implements constructed fromalloys oi. metals of the iron group and the sixth group of the periodicsystem of the elements. e. g.. constructed from chrome-nickel alloys.Thus, for example, the life of a 0.4 mm. wire in the form of a smallspiral wound on a 3 mm. mandrel heated electrically to 1050* C. foralternate periods of two minutes with interposed breaks oi 2 minutes,was about 120 hours. A similar wire made of the same alloy with anaddition of 0.2% oi a metal of the cerium group or 0.2% of cerium mixedmetal i. e., cerium mixed or alloyed with other metals of the rareearths had a life period oi about 200 to 280hours. Higher percentages ofcerium give a corresponding increase in improvement except that withsixth group of the periodic system 0! the elelarger additions the eiiectis not wholly proportional to the amount introduced, a content of about0.84% of cerium or "cerium mixed metal" iving about the maximum effect acontent 01' 1.2% being the upper limit coming into consideration.

The addition of metals of the rare earths required for obtaining anappreciable increasing oi the lite period of heat resisting implementssuch as heating wires or hands for electrically heated furnaces,structural elements or the inner parts of heating and annealingfurnaces, e. g. conveying chains, supporting sheet metal, pyrometerprotecting tubes 81c, need be very small, inasmuch as additions of 0.02percent of rare earth metals to the molten base metal or a content of0.01% in the final alloy already suillce to give a noticeable efl'ect.The base metal for the heat resisting implements to which the rare earthmetals are added may contain besides metals oi the sixth group or theperiodic system of the elements metals of the iron group as the mainconstituent, namely 50 to 98% of nickel, and up to 48% of iron or ironplus cobalt, the amount of cobalt not exceeding 20% oi the final alloy.The percentage of the metals of the sixth group oi the periodic systemof the elements namely chromium, molybdenum, tungsten and uranium mayamount to 1 to 48%, the chromium contents being 1 to 30%: the amount ofeach 0! the metals molybdenum. tungsten and uranium should not exceed20%. When several of the elements cobalt molybdenum, tungsten anduranium are contained at the same time in the alloy, their sum shouldnot exceed 20%. The alloys may further contain small additions fordeoxidation or for improving the malleability such as manganese.magnesium or silicon each up to an amount of 2%, the sum of theseadditions not exceeding 2%.

I claim l. A high temperature oxidation resistant alloy containing .01to 1.2% Ce, 1 to 30% Cr, the balance consisting of iron group metals.

2. A high temperature oxidation resistant alloy containing .01 to 1.2%Ce, 1 to 30% Or, the balance consisting of at least one of the metals ofthe iron group.

3. A high temperature oxidation resistant alloy containing .01 to 1.2%Ce, 1 to 30% Cr, up to 2% 01' a deoxidizer from the group consisting ofmanganese silicon and aluminum and the balance consisting of at leastone of the metals of the iron group.

4. A high temperature oxidation resistant alloy containing .01 to 1.2%Ca, 1 to 30% Cr, a small but eil'ective amount up to 20% Co, the balanceconsisting of nickel.

